/**
 * Copyright 2020 Alibaba Group Holding Limited.
 *
 * <p>Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of the License at
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.maxgraph.sdkcommon.common;

import net.jcip.annotations.ThreadSafe;

@ThreadSafe
public abstract class AbstractRefreshable extends AbstractBaseClient {
    private volatile long sharedVersion = 0;
    private final ThreadLocal<Long> localVersion = ThreadLocal.withInitial(() -> 0L);
    private final Object lock = new Object();

    public AbstractRefreshable(int retries) {
        super(retries);
    }

    @Override
    public void refresh() throws Exception {
        if (this.localVersion.get() == this.sharedVersion) {
            synchronized (lock) {
                if (this.localVersion.get() == this.sharedVersion) {
                    doRefresh();
                    this.sharedVersion = System.currentTimeMillis();
                }
            }
        }

        this.localVersion.set(this.sharedVersion);
    }

    protected abstract void doRefresh() throws Exception;
}
